1. Technical Field
A photoresist composition for resist flow process and a method for forming a contact hole using the same are disclosed. In particular, a photoresist composition comprising a crosslinking agent represented by Formula 1 or Formula 2 which improves resist flow properties, L/S pattern resolution and contrast ratio is disclosed. 
wherein R1, R2, R3 and R4 individually represent H; or substituted or unsubstituted linear or branched (C1-C10) alkyl. 
wherein R5, R6 and R7 individually represent H; substituted or unsubstituted linear or branched (C1-C10) alkyl; or substituted or unsubstituted linear or branched (C1-C10) alkoxy.
2. Description of the Related Art
Resist flow is a processing technology for forming a fine contact hole which exceeds the resolution of the exposing device.
The resist flow process has recently made remarkable developments and so that it is now used in mass production processes. The technology generally involves an exposure process and a development process. This process forms a photoresist contact hole having a resolution equal to that of the exposing device. The process also includes heating the photoresist to a temperature higher than the glass transition temperature of the photoresist which causes the photoresist to flow. The contact hole gets smaller by the flow of photoresist until a fine contact hole necessary for the integration process is obtained.
Thus, the resist flow process makes it possible to obtain contact holes smaller than the resolution of an exposing device. Unfortunately, the resist flow process can result in a sudden or excessive photoresist resin flow (i.e., xe2x80x9coverflowxe2x80x9d) which may result in a bent or collapsed contact hole pattern profile. This problem occurs typically at a temperature higher than the glass transition temperature of the photoresist resin.
The overflow can occur due to several factors including photoresist""s sensitivity to heat, imprecise temperature control, and imprecise control of the flow time.
For example, when the conventional photoresist is used, a bent or collapsed contact hole pattern may occur. Without being bound by any theory, it is believed that this is due to the difference in flowable amount of the polymer present in the upper, center and lower portions of the contact hole pattern. Normally, the amount of flowable polymers in the upper and lower portions is relatively less than that of in the central portion. Therefore, when the same amount of heat energy is irradiated to the photoresist film, the upper and lower portions of photoresist less flow than the central portion of photoresist to form bent patterns.
Attempts to solve the overflow problem by improving the baking process, such as maintaining a uniform baking temperature and/or controlling the precise baking time, have been mostly unsuccessful. In addition, the baking process itself was found to be ineffective to solve the overflow and the bent pattern problems.
An improved photoresist composition for resist flow process is disclosed.
An improved resist flow process for forming a photoresist pattern using such photoresist composition is also disclosed.
A contact hole formation method employing the photoresist pattern formed by the above-described process is also disclosed.